This invention relates to a DC-to-DC converter, particularly, to the type referred to as a ringing converter.
A ringing converter has a simple circuit construction and has its input and output sides DC-separated by means of a transformer. For this reason a ringing converter is often used as a low-power DC-to-DC converter in apparatus of the type in which the internal circuitry of the apparatus is to be DC-separated from the power supply. A ringing converter of such type may comprise a blocking oscillator including a single transistor and a transformer having primary, secondary and positive feedback windings, and a rectifier circuit for rectifying the AC voltage developed by the secondary winding of the transformer. In operation, a direct current which applied to the blocking oscillator is converted into a prescribed AC voltage thereby, the prescribed AC voltage then being rectified by the rectifier circuit in order to obtain a DC voltage of a prescribed voltage value. A disadvantage encountered in the conventional ringing converters is that the DC voltage output fluctuates widely when there is a change in the load current on the output side, or when there is a fluctuation in the DC voltage input. The conventional ringing converters therefore are not suitable for application to power supplies connected to electronic circuits that demand relatively stable power supply voltages.